The best thing you can do is run as far down the platform as you can (in the opposite direction from where the train enters the station) and wave your arms frantically to get the train operator and passenger’s attention. Believe me, the passengers WILL be doing the exact same thing, as nobody wants to see you get run over and their train get delayed. If you can get to the far end of the platform, it gives the train more room to stop, and there is a ladder at the end of each platform where you can climb back up — do NOT try to climb up from where you are. So many people have been killed trying to jump back up rather than getting away from the entrance end of the station. Do NOT trust the pits between the tracks —- they are often right next to the third rail which can be just as dangerous (and note that the wooden planks are not designed to hold a human’s weight - they are there to protect the energized rail from drips and weather) and the train operator is less likely to see you if you’re in there. And don’t duck under the train, because most stations do not have enough clearance for the average human. And do NOT jump down onto the tracks to try to save someone else. The best thing you can do is run on the platform towards the tunnel where the train enters so you can get the operator’s attention sooner. Waving your arms over the tracks will tell the operator to stop immediately.